Since the 1970's there has been a great need to use rapidly moving doors in buildings for industrial use, collectively referred to as industrial doors. This applies to openings indoors as well as in external walls, where the door provides shielding between different activities or prevents drafts and heat losses. One type of industrial doors are, rolling doors. Rolling doors are often formed with flexible door leaves are used for this purpose, but also more rigid constructions like slatted doors with polymeric or metallic lamellae are used. In one known example, these doors are rolled up on an overhead drive cylinder or on two independently driven disks and can be provided with additional elements like transverse wind reinforcements on the door leaf to counteract wind load, a weight balance system, tensioning system, windows or the like. For safety reasons, rolling doors can be further provided with safety edge protection, failsafe devices, drop protection, and crash safety functions.
In most vertically running roller door assemblies, the doors typically run between two rigid door guides. This results in the door and more particularly the door leaf running in an opening in the guide.
Another known industrial door is the vertical lifting door, where the door is lifted either straight up, or at an angle in order to open the door and allow a user to pass therethrough.
In some instances, a roller door or vertical lifting door will be connected to either flexible pulling devices hinge belts, traditional stiff hinges, or a sealing material that tends to yield on impact. One example of such a devices and be found in the commonly assigned PCT application WO 04/076795, which is incorporated herein by reference. The advantage of these devices is that they assist in increasing the speed of the door. Generally the lamellae are laterally connected to the flexible pulling devices or hinge belts. These hinge belts or pulling devices are positioned in the guide of the door and are closely connected to the lamellae either by direct connection or via an end piece which itself is connected to the lamellae. In the event of a crash the end piece may be pulled out of the guide and off the hinges. Alternatively the pulling belts can be torn off. To rebuild the door then takes considerable amounts of time and effort.
In WO 03/018950 there is described a lifting door system which assists in reducing the damage caused by crashes. In the system the described in the '950 application, the end pieces are movably connected to the lamellae, this is typically a horizontally movable connection. As a result when impacted up to a certain point, the lamellae simply move in the joint between the lamellae and the end piece and no damage is done to either the lamellae or the end piece. However, if the impact is severe, and the movement of the lamellae is such that it exceeds the distance provided for in the end piece, the movement of the lamellae may cause damage to the lamellae, the driving components, or the end pieces. Alternatively, the lamellae may be connected to the end piece with a breakable connection, wherein the breakable connection allow the lamellae to break away from the end pieces of the door, and limit the damage to these end pieces.
This lifting door system, however, has certain disadvantages including the inability to optimize the performance of the door, and more importantly, during times of very high wind forces, the lamellae can actually be forced out of the end piece. As is readily apparent such an arrangement provides limited security and may be susceptible to burglary or intruders. In the case where the end pieces have a set breaking point, both parts the lamellae and the end piece may be damaged at a breakage and require replacement.
While some of the foregoing references have certain attendant advantages, further improvements and/or alternative forms, are always desirable.